Storage System

ABSTRACT

There is provided a storage system including a file server connecting to a computer over a network and a storage apparatus connecting to the file server connecting over the network, wherein the file server includes a first controller, the storage apparatus includes multiple storage devices having multiple storage areas and a second controller that controls accesses to the multiple storage areas, each of the multiple storage areas has at least one power saving mode among multiple power saving modes with different shift times from the power saving modes to a ready mode, the first controller, in response to the reception of data from the computer, sets an indicator relating to the performance of response to an access from the computer to the data and refers to the indicator of the data and selects a first storage area having the power saving mode satisfying the indicator, and the second controller stores the data to the first storage area.

CROSS REFERENCES TO RELATED APPLICATIONS

This application relates to and claims priority from Japanese PatentApplication No. 2008-177423, filed on Jul. 7, 2008, the entiredisclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a storage system, and it particularlyrelates to a storage system having a power saving function for a storagedevice and a control method therefor.

Hitherto, a storage system has been known that includes a server and adisk array subsystem including an array of multiple hard disk drives(which will be called HDD hereinafter) for providing storage areas tothe server.

The server uses the disk array subsystem for multiple applications, andone application is that the server uses the disk array subsystem forarchiving. By the way, keeping the HDDs on at all times which are notfrequently accessed is not preferable from the viewpoint of power savingin the disk array subsystem. Accordingly, a power saving technologycalled MAID (or Massive Array of Inactive Disks) is applied to thestorage system. The accesses include a read request and a write request.

MAID refers to a technology that reduces the power consumption byterminating the rotation of a disk in an HDD without any data access orshutting down the power supply to an HDD in a disk array. Since a diskarray that adopts MAID is controlled to only operate the HDD thatrequires data access, the power consumption can be reduced.

On the other hand, several power saving modes employing the MAIDfunction according to the degree of the power saving function have beenknown such as a mode that shuts down the power supply to a chassiscontaining multiple HDDs, a mode that shuts down the power supply to anHDD and a mode that terminates the rotation of a disk in an HDD. A diskarray system has also been known that includes multiple logical unitswith the hierarchy of degrees of the power saving function and,according to the frequency of the access request to one logical unit,moves the data stored therein to a logical unit applying a differentpower saving mode (JP-A-2008-90352).

Patent Document 1: JP-A-2008-90352

SUMMARY OF THE INVENTION

Since the conventional disk array subsystem may not determine beforedata storage whether the archive data to be written from the server isonline data that requires a high accessibility from the server, offlinedata that requires a lower accessibility from the server or near-linedata that requires the accessibility between online data and offlinedata from the server, data cannot be stored in an HDD having anappropriate power saving function.

Therefore, the conventional disk array subsystem has a possibility thatonline data may be stored in an HDD applying the mode that shuts downthe power supply to the HDD, which is a power saving mode having a highpower saving effect but taking time for response. Then, when an accessrequest to the online data occurs from the server, there is apossibility that the performance of response to the access to the onlinedata may be reduced, and the access from the server may timeout.

Accordingly, it is an object of the present invention to provide astorage system having a function of saving power to a storage device andcontrol method therefor, which do not reduce the performance of responseto an access from a server to the storage device.

According to an aspect of the invention, there is provided a storagesystem including a file server connecting to a computer over a networkand a storage apparatus connecting to the file server connecting overthe network, wherein the file server includes a first controller, thestorage apparatus includes multiple storage devices having multiplestorage areas and a second controller that controls accesses to themultiple storage areas, each of the multiple storage areas has at leastone power saving mode among multiple power saving modes with differentshift times from the power saving modes to a ready mode, the firstcontroller, in response to the reception of data from the computer, setsan indicator relating to the performance of response to an access fromthe computer to the data and refers to the indicator of the data andselects a first storage area having the power saving mode satisfying theindicator, and the second controller stores the data to the firststorage area.

According to another aspect of the invention, there is provided acontrol method for a storage system, the storage system having a fileserver connecting to a computer over a network and a storage apparatusconnecting to the file server connecting over the network, the storageapparatus including multiple storage devices having multiple storageareas and controlling accesses to the multiple storage areas, the methodincluding the steps of setting each of the multiple storage areas in atleast one power saving mode among multiple power saving modes withdifferent shift times from the power saving modes to a ready mode by thestorage apparatus, setting an indicator relating to the performance ofresponse to an access from the computer to the data received from thecomputer by the file server and referring to the indicator of the dataand selecting a first storage area having the power saving modesatisfying the indicator by the file server; and storing the data to thefirst storage area by the storage apparatus.

According to the invention, there can be provided a storage systemhaving a function of saving power to a storage device and control methodtherefor, which do not reduce the performance of response to an accessfrom a server to the storage device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a storage control system including astorage system according to one embodiment of the invention;

FIG. 2 is a block diagram illustrating programs in a file serveraccording to one embodiment of the invention;

FIG. 3 shows a first management table according to one embodiment of theinvention;

FIG. 4 shows a second management table according to one embodiment ofthe invention;

FIG. 5 is a block diagram showing a structure of metadata according toone embodiment of the invention;

FIG. 6 is a block diagram illustrating a general outline of an operationfor storing data in a storage apparatus by the file server according toone embodiment of the invention;

FIG. 7 is a block diagram illustrating the definition of the managementtable to the file server according to one embodiment of the invention;

FIG. 8 is a flowchart for creating a folder in File System by the fileserver according to one embodiment of the invention;

FIG. 9 is a flowchart illustrating an operation for storing datareceived from a service server to the storage apparatus by the fileserver according to one embodiment of the invention;

FIG. 10 is a flowchart illustrating a power supply control operationaccording to one embodiment of the invention;

FIG. 11 is a flowchart for shifting storage devices in the storageapparatus into a power saving mode according to one embodiment of theinvention;

FIG. 12 is a flowchart illustrating a processing operation by the fileserver in a case where the TOV indicator of metadata is changedaccording to one embodiment of the invention;

FIG. 13 shows a variation example of that in FIG. 10 and is a flowchartillustrating a power supply control operation according to oneembodiment of the invention;

FIG. 14 shows a variation example of that in FIG. 11 and is flowchartfor shifting the storage devices in the storage apparatus into a powersaving mode according to one embodiment of the invention;

FIG. 15 is a variation example of that in FIG. 9 and is flowchartillustrating an operation for storing data received from the serviceserver to the storage apparatus by the file server according to oneembodiment of the invention;

FIG. 16 is a variation example of that in FIG. 9 and is a flowchartillustrating the operation for storing data received from the serviceserver to the storage apparatus by the file serve according to oneembodiment of the invention r; and

FIG. 17 is a table managing the movement of files according to oneembodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the invention will be described next. FIG. 1 is a blockdiagram of a storage control system including an example of the storagesystem according to the invention. The storage control system includes aservice server 10 positioned as a host system for a storage apparatusand a storage system including a file server 16 and a storage apparatus30. The file server 16 and the storage apparatus 30 may be placed withinone chassis.

The service server 10 is a computer apparatus including informationprocessing resources such as a CPU and a memory. The service serverincludes an information input device such as keyboard switches, apointing device and a microphone and an information output device suchas a monitor and a speaker.

The service server 10 recognizes the storage structure with a filesystem of the file server 16 and writes and reads data to and from thefile system. The service server 10 may include archiving software forproviding an archive solution to a client. The service server 10 mayprovide an operation application to a management client, excludingarchiving software.

A network 12 connects to a port 14 of a LAN interface controller of eachof the multiple service servers. A port 18 of the LAN interface of thefile server 16 connects to the network 12. The service server 10connects to the file server 16 over the network 12.

The file server 16 further includes a microprocessor 24, a cache memory21 and a local memory 22, in addition to the port 18. Those devicesconnect to each other through a connecting unit 20. The cache memory 21is a memory that temporarily saves data transmitted from the serviceserver 10. The local memory 22 stores programs and managementinformation for implementing control functions of the file server 16.

FIG. 2 is examples of the programs that implement functions of the fileserver 16. The programs are stored in a local memory 22. Themicroprocessor 24 then executes the programs to implement the functionsof the file server. Gateway provides a communication protocol requiredfor communication with the service server 10 to the microprocessor 24.File System recognizes a file access from the service server 10 anddetermines the storage area, which will be a destination of the dataaccess from the service server 10.

Request Manager processes an access from the service server 10 andperforms processing such as creation and update of metadata. StorageManager performs processing for reading/writing from/to the storageapparatus 30. Metadata Manager performs processing for reading/writingfrom/to metadata.

The file server 16 further includes a port 26 for a fiber channelinterface controller, and the port 26 connects to a network 28. Thenetwork 28 may be an SAN. The file server 16 requests a storageapparatus to input/output data in blocks, each of which is a managementunit of a storage area of an HDD, according to Fiber Channel Protocol.

The storage apparatus 30 includes an HDD as a storage device. Thestorage apparatus 30 may be a disk array subsystem including multipleHDDs. Without limiting thereto, a part of storage devices may besemiconductor memories such as a flash memory.

The storage apparatus 30 has multiple disk drive units 54A to 54D asstorage devices and multiple disk adapters (DKAs) 40 which control theinput/output of data to/from the disk drive units. Each of the DKA 40has a port 42 connecting to the disk drive units. The ports 42 and thedisk drive units are connected by an FC-AL or Fabric of Fiber Channel oran SAS, for example.

The storage apparatus 30 includes multiple channel adapters (CHAs) 32each functioning as an interface controller for the file server 16. Eachof CHAs has a port 34. Connecting the port 34 to the network 28 connectsthe storage apparatus 30 to the file server 16.

The CHAs 32 and the DKAs 40 are connected through a connecting unit (orconnecting circuit) 36. The connecting unit 36 further connects to ashared memory (SM) 38 and a cache memory (CM) 34. Each of the CHAs 32includes a microprocessor (MP) and a local memory (LM) that stores amicroprogram to be executed by the MP for processing a commandtransmitted from the file server 16. Each of the DKAs 40 includes an MPand an LM to be used by the MP for executing a microprogram forcontrolling the multiple disk drive units.

In order to perform interlocked processing between the multiple CHAs 32and the multiple DKAs 40, control information to be shared by themexists in the shared memory 38. In response to the reception of areadout or write command for data from the file server 16, thecorresponding CHA 32 stores the command to the shared memory 38. The DKA40 refers to the shared memory 38 at all times, and, if any unprocessedreadout command is found, reads out data from a corresponding HDD andstores it in the cache memory 34.

The CHA 32 reads out the data moved to the cache memory 34 and transmitsit to the file server 16 having issued the command. In response to thereception of a data write request from the file server 16, thecorresponding CHA 32 stores the write command in the shared memory 38and stores the receive data in the cache memory 34. The DKA 40 storesthe data stored in the cache memory 34 in an HDD according to thecommand stored in the shared memory 38.

The DKA 40 converts a logical address accompanying the command from thefile server 16 to a physical address in an HDD upon input/output of datato/from the HDD. Each of the DKAs 40 performs data access according tothe RAID configuration of a corresponding HDD.

Each of the DKAs monitors the modes including power saving modes of HDDsat all times, and the monitoring results are transmitted to an SVP (orservice processor) 50 through a LAN interface 48 connecting to theconnecting unit 36. The SVP 50 is a computer apparatus (or managementdevice) that manages and monitors the storage apparatus. The SVPcollects environmental information and performance information, forexample, from the CHAs 32 and DKAs 40 through the connecting unit 36.

A work area is defined in the shared memory 38, and the shared memory 38stores a first management table (refer to FIG. 3) and second managementtable (refer to FIG. 4), which will be described below.

The connecting unit 36 may be configured as a high-speed bus such as anultra-high speed crossbar switch that performs data transmission basedon a high-speed switching operation.

The storage apparatus 30 includes a control interface port 46 connectingto a control signal 44 connecting to a power supply circuit (or PDB:Power Distribution Block) 52 that controls the power supply to the diskdrive units 54A to 54D. The power supply control circuit 52 includesswitches 51A to 51D that turn on/off the power supply to the multipledisk drive units 54A to 54D.

Each of the switches 51A to 51D connects to one of the disk drive units54A to 54D, and each of the disk drive units includes multiple HDDs 60Ato 60N (or 62A to 62N, 64A to 64N or 66A to 66N). If one switch of thepower supply control circuit 52 is opened, the power supply to all ofthe HDDs belonging to the disk drive unit connecting to the switch isshut down. Therefore, the power supply to the HDDs is turned off (whichis called disk drive unit off mode). With one switch of the power supplycontrol circuit closed, the power can be supplied to the multiple HDDsincluded in the disk drive unit connecting to the switch. Therefore,they can be controlled into a power saving mode by the DKA 40. The powersaving mode may be a mode in which the power supply to an HDD is off(which will be called HDD off mode), a mode in which the rotations ofthe disk in an HDD stop (which will be called spin down mode), a mode inwhich the disk in an HDD rotates at a lower rotational speed (which willbe called low rotational speed mode) or a mode in which the head of anHDD is unloaded from the above of a disk (which will be called headunload mode). The switches of the power supply control circuit arecontrolled by the MP of the CHA or the MP of the DKA.

Referring to FIG. 1, the “Active” in the HDDs means that they are in amode that the HDDs are ON and at a high rotational speed, which is aready mode in which data can be immediately written thereto according toa write command or data can be immediately output therefrom according toa read command. The “Inactive” means that the corresponding HDD is in apower saving mode such as the HDD off mode, spin down mode, lowrotational speed mode, head unload mode and disk drive unit off mode.

The DKA 40 of the storage apparatus has a power supply control programin a local memory of the DKA 40 for shifting the HDD from the ready modeto the power saving mode. Then, the MP of the DKA executes the program.The CHA 32 and the DKA 40 execute a manager program for read or writeprocessing on an HDD.

If an HDD is in the power saving mode, the storage apparatus, in orderto respond to a write command or a read command, must shift the HDD tothe ready mode once, which reduces the performance of response of theHDD to the write command and the read command and results in thetimeout.

Accordingly, the service server 10 or file server 30 sets an indicatorbased on an acceptable timeout value (which will be called TOV indicatorhereinafter) as an indicator indicative of the access performance ofresponse from the service server 10 to the data for which write requestis transmitted from the service server 10 to the file server 30 shown inFIG. 1. On the other hand, a logical unit (or LU) including at least oneHDD is classified based on the indicator. For example, the LU includingthe HDD off mode as the power saving mode is classified to the “Offline”with a longer TOV value as an indicator on the accessibility. Then, thefile server 16 compares the TOV indicator of the data and the TOVindicator of the logical unit and stores the data in the HDD of thelogical unit which is matched with the indicator of the data.

The storage apparatus or file server sets the TOV value as an acceptabletime for responding to each write access or read access. Without anyresponse from an HDD even after a lapse of the TOV value, the storageapparatus or file server determines it as a write error or read error.

The data not requiring high access performance of response for accessesfrom a host system and accepting a higher TOV value (on the order ofseveral minutes) in responding to an access is called “offline data”. Astorage device for storing offline data is set in a disk drive unit offmode or HDD off mode, for example, as the power saving mode, requiring atime of several minutes for the shift from the power saving mode to theready mode. Those storage devices have “Offline” as the TOV indicator.According to this embodiment, the HDD off mode is set therefor.

On the other hand, data requiring high access performance of response toan access from a host system and accepting a lower TOV value (on theorder of several seconds) in responding to an access is called “onlinedata”. A storage device for storing the online data may be set in theready mode at all times or may be set in the head unload mode or lowrotational speed mode, which can be shifted to the ready mode in a shortperiod of time on the other of several seconds among the power savingmodes. According to this embodiment, the ready mode is set therefor atall times. Those storage devices have “Online” as the TOV indicator.

The data requiring the access performance of response in the middle (onthe order of several tens seconds) between those of Online data and Offline data is called “near line data”. The storage device for storing thenear line data is set in the spin down mode, as the power saving mode,requiring a time of several tens seconds for shifting from the powersaving mode to the ready mode. Those storage devices have “Near Line” asthe TOV indicator.

The operation modes of the storage devices for storing the online data,near line data and offline data are not limited thereto but can bechanged as required based on the relationship between the TOV value andthe time for shifting from the power saving mode to the ready mode.

FIG. 3 is a first management table showing the correspondencerelationships among the disk drive units, HDDs and LUs, the power supplystate of the disk drive units, the current operation modes of the HDDsand the power saving modes supported by the HDDs. FIG. 4 is a secondmanagement table showing the current operation modes of the LUs, the TOVindicators indicative of the access performance of response of the LUsand the power saving modes supported by the LUs. With reference to thefigures, description will be given below.

In FIG. 3, “Disk Drive Unit #” is a symbol for identifying each of thedisk drive units 54A to 54D of FIG. 1, “Disk drive unit Operation Mode”is a mode in which the power supply to the disk drive unit is performed(ON) or the power supply is shut down (OFF), “HDD#” is an identificationnumber of an HDD belonging to each of the disk drive units, “the HDDOperation Mode” is the current operation mode (which is the ready modeor one of the power saving modes) of each of the HDDs, “LU#” is anidentification symbol of a logical unit (LU), “Mode Allowing Designationof Power Supply Control For HDD” is information describing the powersaving function supported by each of the HDDs among the power savingfunctions. “Full Time ON” describes whether the mode in which the powersupply of an HDD is ON at all times is supported or not, “Low RotationalSpeed” describes whether the low rotational speed mode is supported ornot, “Spin Down” describes whether the spin down mode is supported ornot, and “OFF” describes whether the HDD off mode is supported or not.

Under “Mode Allowing Designation of Power Supply Control For HDD”, “Yes”means the corresponding HDD supports the power saving functions, and“No” means that the HDD does not support the power saving functions.

Which HDD is to be included in each of the LUs may be designated by amanagement client through the SVP or may be designated by the storageapparatus based on the information on the HDD. In this case, each of theLUs is preferably defined to include multiple HDDs supporting same powersaving modes. Here, whether same power saving modes are supported or notmay be determined based on whether at least one same power saving modeis supported or not since all of the power saving modes are not requiredto be completely the same.

Here, the management client of the SVP can discriminate each of themultiple disk drive units and can discriminate each of the multipleHDDs. The DKA 40 can recognize the operation modes of the disk driveunits and the power saving mode of the HDDs based on the statusinformation from the disk drive units and HDDs.

In FIG. 4 on the other hand, “LU#” is an identification symbol of an LU,and “LU Operation Mode” describes whether the HDDs included in the LUare in the ready mode or in one of the power saving mode. Generally, themultiple HDDs included in the LU have a same operation mode. Forexample, all of the HDDs included in an LU 1 in the disk spin down modehave the spin down mode in FIG. 3. “TOV Indicator” is an indicatorrelating to the access performance of response in a case where an accesscommand is received from the service server in the power saving mode.“Mode Allowing Designation of Power Supply Control For LU” is an item ofthe power saving function supported by the LU#. Therefore, it isdetermined by the power saving function supported by the multiple HDDsincluded in the LU#. The meanings of the items are the same as those inFIG. 3. “Disk Drive Unit OFF” refers to whether the disk drive unitbelonging to an LU supports the disk drive unit off mode or not.

The “TOV indicator” of the second management table is determined by thesetting of the power saving mode of the multiple HDDs included in an LU.That is, according to this embodiment, in order to set “Online” as theTOV indicator, the HDDs included in an LU must be at least in the readymode at all times. Similarly, in order to set “Near Line”, the HDDsincluded in an LU must be at least in the spin down mode. Similarly, inorder set “Offline”, the HDDs included in an LU must be at least in theHDD off mode.

FIG. 5 shows a structure of metadata. The metadata is provided for eachfile and is created or updated every time the file is created orupdated. The opportunity for the update is not limited thereto, but themetadata may be updated as required by a management client or may beconfigured to update automatically after a lapse of a predeterminedperiod of time. The metadata includes the date and time of creation,saving period, TOV indicator and date and time of the last access. TheTOV indicator may be a TOV (such as XX seconds and XXX minutes) itselfor may be Online, Offline or Near Line.

FIG. 6 is a block diagram showing an example of the general outline ofthe operation by the file server 16 for storing data to the storageapparatus 30. After the server 10 stores data to a file 60 in the fileserver 16 over the network 12 (S1), File System stores the file 60 to adata area (such as a cache memory) 21A. On the other hand, File Systemcreates or determines the metadata from the file information and storesit to a metadata area 62. The metadata area is stored in the localmemory 22. A storage manager of the file server 16 designates thelogical volume (LU) in the storage apparatus 30 having an indicatormatched with the TOV indicator contained in the metadata of the data ofthe file (S2). The management client can change the attribute of thefile and, if the change in attribute of the file relates to the TOVindicator, the data of the file is moved from the storage area storingthe data to a storage area supporting the changed TOV indicator (S4).

If the file server receives a write command or read command on data fromthe service server, the LU for storing the data is determined. Then, ifthe destination LU operates in the power saving mode, the storageapparatus shifts the power saving mode of the HDDs to the ready modeaccording to the instruction from the file server. Then, after a lapseof a predetermined period of time with reference to the date and time ofthe last access in FIG. 5, the storage apparatus shifts the ready modeof the HDDs to the power saving mode according to the instruction fromthe file server. The ready mode of the HDDs may be shifted to the powersaving mode according to the instruction by the management client.

The instruction by the file server may be implemented by issuing acommand to the storage apparatus. In issuing the command for shifting tothe power saving mode or to the ready mode to the storage apparatus, thefile server identifies not only an LU but also an HDD included in the LUas the storage area.

On the other hand, in a variation example, which will be describedlater, the file server only holds the second management table shown inFIG. 4, which is referred to identify an LU as the storage area to issuethe command to the LU. The storage apparatus having received the commandrefers to the first management table to determine the HDD included inthe LU. The details will be described later.

First of all, the operation will be described for setting the firstmanagement table shown in FIG. 3 and the second management table shownin FIG. 4 to the file server. FIG. 7 is a flowchart illustrating theoperation for defining the first management table and the secondmanagement table.

If Request Manger of the file server 16 receives an LU discovery requestfor the storage apparatus from the management device of the file server,Request Manager requests the storage apparatus 30 the first managementtable and the second management table (700). The CHA 32 of the storageapparatus receives the request (702), loads the first management tableand second management table from the shared memory 38 and transmits thefirst management table and second management table to Request Manager ofthe file server (704). Request Manager receives the first managementtable and second management table (706) and then stores them to thelocal memory 22 (708).

The file server may receive information corresponding to the items onthe first management table and second management table from the storageapparatus and may create and store the first management table and secondmanagement table in the file server.

The support information of the power saving modes of an HDD may beobtained by obtaining product information of the HDD by the DKA uponinstallation of the HDD to the storage apparatus, replacement of the HDDor addition of an HDD. The management client may input the supportinformation through the SVP.

Next, the method for setting a file system based on the TOV indicator ofdata in the file server will be described. After the service server 10stores data to a file system of the file server, the TOV indicator isset to the metadata shown in FIG. 5. While the file system according tothis embodiment has a folder directory structure, the structure is notlimited thereto. FIG. 8 shows a flowchart for creating a folder in FileSystem by the file server. First of all, the service server 10 issues acommand for creating a folder to the file server 16 (800). RequestManager receives it (802) and then checks whether the folder creationcommand contains a TOV indicator or not (804).

If Request Manager determines so (804: Y), Request Manager checks thesecond management table and determines whether any LU exists that ismatched with the TOV indicator contained in the command or not (806). Ifnot (806: N), an error may be indicated to the service server (808), andthe service server may be prompted to create a folder again. The fileserver may create an LU having an indicator corresponding to the TOVindicator contained in the command. If a matched LU exists (806:Y),Request Manager creates a folder in the corresponding LU (810) andcreates the metadata of the folder (812). After that, Request Manager ofthe file server issues a completion report (814) and the processing endswhen the service server receives it (815).

If the folder creation request command does not contain the TOVindicator (804: N), whether any higher level folder than the folder tobe created exists or not is determined (816). If so (816: Y), the TOVindicator of the metadata of the higher level folder is set to themetadata of the folder to be created (818). On the other hand, if nofolders exist at a higher level than the folder to be created (816: N),a default TOV indicator (such as Online) is set to the folder to becreated (820), and the metadata of the folder is created.

After the management client of the service server stores the file in thefolder having the TOV indicator aimed by the management client, the fileserver reflects the TOV indicator set to the metadata of the folder tothe TOV indicator of the metadata of the file. The folder may be anonline data folder, a near-Line folder or an offline folder.

Next, operations will be described for storing data of a file to thestorage apparatus by the file server and for saving power to an HDD inthe storage apparatus. FIG. 9 is a flowchart of an operation forreceiving a file from the service server 10 and storing the file to thestorage apparatus by the file server 16. After receiving a file from theservice server (900), Request Manager of the file server 16 stores thedata to the cache memory 21 (902) and reports the completion to thewrite command from the service server (904).

With reference to the metadata of the folder of File System storing thefile, Request Manager sets a TOV indicator to the metadata of the file(906) and saves the metadata to a metadata folder.

Next, with reference to the TOV indicator of the metadata of the file,Request Manager selects an LU# having an indicator matched with the TOVindicator from the second management table (908). Next, with referenceto the operation mode of the LU#, whether the operation mode of the LUis the ready mode allowing immediate storage of data or not isdetermined (910). If it is in the ready mode, Storage Manager determinesan HDD included in the LU from the first management table and transmitsthe data and the identification information of the HDD for storing thedata to the storage apparatus. After that, the DKA of the storageapparatus stores the data to the HDD (914).

On the other hand, if the LU is not in the ready mode, Storage Managershifts to a power supply control operation (912) of the HDD for shiftingit to the ready mode. FIG. 10 is a flowchart of the power supply controloperation. Request Manager identifies an HDD included in the LU and adisk drive unit including the HDD based on the first management table.

With reference to the operation mode of the disk drive unit on the firstmanagement table, Request Manager determines that the disk drive unit isready if the operation mode is ON and determines that it is not ready ifthe operation mode is OFF (1000). If it is determined as not ready,Request Manager requests the power supply control program in the storageapparatus a command to shift the disk drive unit into the ready mode(1002). The storage apparatus having received the request sets 0 to acontrol symbol (X) for determining whether it is beyond an upper limitvalue of the number of times of implementation of the processing forshifting the disk drive unit to the ready mode or not (1004 and 1006)and outputs an instruction to turn on the switch connecting to the diskdrive unit to the power supply control circuit 52 (1008).

The power supply control program determines whether the power supply tothe disk drive unit has been turned on or not (1000). If not, thecontrol symbol (X) is incremented (1006), and whether the control symbolafter the increment is equal to or higher than a maximum value Y or notis determined (1008). If not, the power supply to the disk drive unit isturned on again. If so, a failure notification is performed to the fileserver since it is beyond the upper limit value of the processing forshifting the disk drive unit to the ready mode (1020).

If the LU has multiple applicable disk drive units (such as the LU 1 onthe first management table), Request Manager and the power supplymanagement program determine whether the power supplies of all of thedisk drive units are ON or not. If not, an operation is performed forturning on the power supplies to the disk drive units.

If the power supply control program of the storage apparatus determinesthat the processing of turning on the disk drive units has succeeded,the power supply control program updates the operation mode of the diskdrive units on the first management table from OFF to ON (1012) andtransmits a completion report (1014) to Request Manager. After receivingthe completion report, Request Manager updates the first managementtable and second management table stored in the local memory in the samemanner (1022 and 1024).

If Request Manager determines that the disk drive unit is in the readymode (1000) or if the processing of turning on the power supply to thedisk drive unit completes, whether all of the HDDs included in the LUare in the ready mode allowing response to an access request or not isdetermined (1026). If not, the request to shift at least the HDD not inthe ready mode to the ready mode (1028) is transmitted to the powersupply control program of the storage apparatus. The power supplyprogram of the storage apparatus having received the request (1030)shifts all of the multiple HDDs into the ready mode, then updates themanagement tables and transmit them to Request Manager (1030 to 1046),in the same manner as that of the operation for turning on the powersupply of the disk drive unit. After updating the first management table(1048 and 1050), Request Manager moves to the data storage processing(914) in FIG. 9.

The operations on the flowcharts in FIGS. 9 and 10 allow the file serverto store the data in an LU in a sufficient power saving mode accordingto the TOV indicator of the data received from the service server, alsosatisfying the access performance of response of the indicator. In otherwords, online data is stored in an LU set in the ready mode at alltimes. Near line data is stored in an LU set in the spin down mode, andoffline data is stored in an LU set in the HDD off mode.

Therefore, in the file server, even a read request for online data thatrequires a high access performance of response (with a lower TOVindicator) from the service server can be responded by an HDD includedin an LU storing online data within several seconds, and the online datacan be transmitted to the service server quickly. On the other hand,even in response to a read request for near line data or offline datafrom the service server, the file server can transmit the data to theservice server securely within a longer TOV range. Thus, data can bestored in an LU having an appropriate power saving function according tothe access performance of response of the data, such as the TOVindicator. Therefore, the power saving mode that can provide asufficient power saving effect can be used to reduce the powerconsumption, satisfying the accessibility required by the serviceserver.

FIG. 11 is a flowchart illustrating an operation for shifting the readymode of the HDD in the storage apparatus to the power saving mode.Request Manager of the file server repetitively performs the operationon the flowchart at predetermined time intervals. Request Manager scansmetadata folders and checks whether any metadata has the last accesstime to the file beyond a predetermined time or not (1100).

If it is determined so, whether the TOV indicator of the metadata isOnline or not is determined (1102). If so, the processing ends since thepower supply to disk drive units, the power supply to HDDs and therotational speed are not required to control.

If the TOV indicator is not Online, whether the TOV indicator is NearLine or not is determined. If not, Request Manager identifies an LUcorresponding to the folder storing the file in order to shut down thepower supply to the HDDs, refers to the first management table andtransmits a request to shut down the power supply to the multiple HDDscorresponding to the LU (1106) to the power supply control program ofthe storage apparatus.

After receiving the request for shutting down the power supply to theHDDs (1110), the power supply control program of the storage apparatusshifts the modes of the HDDs so that the DKA can turn off the powersupply to the HDDs (1114), updates the operation modes on the firstmanagement table and the second management table (1114), and reports thecompletion to Request Manager (1116). Request Manager having receivedthe report of the completion updates the operation modes on the firstmanagement table and the second management table and exits theprocessing (1118 and 1120).

On the other hand, if the TOV indicator of the metadata is Near Line,Storage Manager transmits a request to shift the multiple HDDs into thespin down mode (1108) to the power supply management program. The powersupply management program receives the request (1110) and then issues acommand to change the power saving modes of the HDDs through the DKA inorder to reduce the rotational speed of the HDDs. In response to thereception of the command, the HDDs not in the spin down mode are shiftedinto the spin down mode (1112), and the power supply control programupdates the operation modes on the first management table and the secondmanagement table to the spin down mode (1114). The file server alsoupdates the operation modes on the first management table and secondmanagement table (1116 to 1120).

In this way, the file server and the storage apparatus can shift theoperation mode of the HDDs from the ready mode to a power saving modethat has been set if the HDDs are not accessed for a predeterminedperiod of time.

Next, with reference to FIG. 12, a processing operation by the fileserver will be described in a case where the TOV indicator of metadatais changed. In a case where the TOV indicator of metadata correspondingto data stored in an LU is changed, the service server issues a requestfor moving the file to the file server. The file server may beconfigured to automatically perform the processing at and subsequent to1200 if the TOV indicator of metadata is changed.

After receiving the request for moving the file from a folder storing itto another folder (1200), the file server recognizes the identificationinformation of a source LU (1202) and the identification information ofa destination LU (1204) from the information on the source folder andthe destination folder. In this case, the file may be moved from afolder for Near Line or Offline to a folder for Online or the reverse,and, with that, this processing changes the destination LU.

Next, Request Manager uses the second management table to determinewhether the source LU and destination LU are in the ready mode or not(1206 and 1208). If not, Request Manager performs the power supplycontrol flow (FIG. 10) such that all of the HDDs included on the LUs canbe in the ready mode (1210 and 1212).

Next, based on the request form Request Manager, the DKA of the storageapparatus loads the data in the source LU from the HDD and temporarilystores it to the cache memory 34 (1214), stores the temporarily storeddata to a storage area of the destination LU (1216) and deletes the datastored in the storage area of the source LU (1218). Then, RequestManager deletes the metadata of the source data from the folder (1220).

According to this embodiment, the file server can recognize an LU in thestorage apparatus and the HDDs corresponding to the LU since it holdsthe first management table and second management table. Then, theservice server sets to the data the tendency of access to the data andstores the data in the HDD having an optimum power saving characteristicto the tendency.

In a variation example, which will be described later, of thisembodiment, the file server does not hold the first management table butholds the second management table. Therefore, the LU for the storagearea can be identified, but the HDDs included in the LU cannot beidentified. If the file server requests to shift an LU into the readymode or into a power saving mode, the storage apparatus identifies andcontrols the HDDs included in the LU. The configuration can reduce theload on the file server. If multiple storage apparatus connect to thefile server, the processing can be distributed. Therefore, theperformance of the entire storage system can be improved. The processingwill be described more specifically below.

First of all, the operation for defining the second management table bythe file server will be described. It is different from the flow in FIG.7 that data to be exchanged between the file server and storageapparatus does not contain the first management table but is the secondmanagement table.

More specifically, if Request Manager of the file server 16 receives anLU discovery request in the storage apparatus from the management deviceof the file server, Request manager requests the storage apparatus 30the second management table (700). If the request is received (702), theCHA 32 of the storage apparatus loads the second management table fromthe shared memory 38 and transmits the second management table toRequest Manager of the file server (704). Request Manager receives thesecond management table (706) and then stores it in the local memory 22(708).

The file server may receive information corresponding to the items ofthe second management table from the storage apparatus and may createand store the second management table in the file server.

The processing of creating a folder is the same as the flow in FIG. 8.The flowchart for creating the folder in File System by the file serveris the same as that in FIG. 9. However, the power supply controlprocessing (912) applies the power supply control processing in FIG. 13,which will be described below. In storing data (914), Request Manager ofthe file server designates a destination LU and identifies the HDDsincluded in the LU in the storage apparatus.

FIG. 13 is a flowchart of the power supply control processing and showsa variation example in FIG. 10, which has been described above.According to the above-described embodiment, the file server siderecognizes the disk drive units including an LU and the HDDs included inthe LU and the storage apparatus controls the operation modes of thedisk drive units and HDDs based on an instruction from the file server.On the other hand, referring to FIG. 13, the file server designates anLU on which the power supply control is performed and issues a commandto the storage apparatus (1300). Then, the storage apparatus havingreceived the command identifies the disk drive unit to which the LUbelongs based on the first management table held by the storageapparatus. Then, the DKA of the storage apparatus determines whether thedisk drive unit is in the ready mode or not (1000). The processing afterthe determination is the same as that (1006 to 1018) in FIG. 10. Next,the storage apparatus identifies the HDDs included in the LU based onthe first management table held by the storage apparatus. Then, thestorage apparatus determines whether the HDDs included in the LU are inthe ready mode or not (1026). The processing after the determination isthe same as that (1032 to 1046) in FIG. 10. When the file serverreceives the report of the completion from the storage apparatus, thefile server updates the operation modes on the second management table(1050).

FIG. 14 is a variation example of the flowchart for shifting the HDDs inthe storage apparatus shown in FIG. 11 into a power saving mode.Referring to FIG. 11, Request Manager of the file server identifies anLU to store data and the HDDs included in the LU and requests thestorage apparatus to shift to a power saving mode. Referring to FIG. 15on the other hand, Request Manager of the file server identifies an LUto store data and requests the storage apparatus to shift to a powersaving mode.

The processing in 1100, 1102 and 1104 is the same as that in FIG. 11.

Next, Request Manager of the file server transmits a request for turningoff the operation mode of the LU to the DKA of the storage apparatus(1400). The DKA receives the request for turning off the operation modeof the LU (1402), then identifies the HDDs included in the LU based onthe first management table and requests to turn off the power supply tothe HDDs (1404). Then, the DKA reports the completion to the file server(1418). In response to the completion, Request Manger of the file serverupdates the operation modes on the second management table (1420 and1422). On the other hand, the storage apparatus changes the modes of theHDDs into the HDD off mode (1408) and updates the first management tableand second management table (1410). Then, the storage apparatusdetermines whether all of the HDDs in the disk drive unit in which HDDsare mounted are turned off or not (1412). If so, the power supply of thedisk drive unit having the HDDs is turned off, and it is reflected tothe update and registration on the first management table (1414 and1416).

Request Manager of the file server transmits to the storage apparatus arequest for shifting the HDDs in an LU to store data into the spin downmode (1424), and the DKA of the storage apparatus receives the request(1426). After receiving it, the DKA transmits the report of thecompletion to the file server, and the file server updates and registersthe second management table (1430). If receiving the request forshifting the LU to into the spin down mode, the DKA of the storageapparatus identifies the HDDs included in the LU based on the firstmanagement table and requests for shifting the HDDs included in the LUinto the spin down mode (1434). After shifting the HDDs into the spindown mode (1438), the first management table and the second managementtable in the shared memory are updated and registered (1440).

Next, variation examples of the method for data storage will bedescribed below. The variation examples are all applicable to the twoembodiments above.

FIG. 15 shows a variation example in FIG. 9 and is a flowchart for anoperation for storing a file data transmitted from the service server tothe file server into a target HDD.

Since the steps 900 to 906 are the same as those in FIG. 9, the samereference numerals are given thereto. In step 908, Request Manager ofthe file server checks whether the TOV indicator for the LU is Online ornot with reference to the second management table (1500).

If Request Manager determines so, the processing moves to data storageprocessing (1502). In the data storage processing, if the local memoryof the file server stores the first management table and the secondmanagement table, the file server identifies a destination HDD andinstructs the storage to the storage apparatus. If the second managementtable is stored in the local memory of the file server, the file serveridentifies a destination LU and instructs the storage to the storageapparatus. Then, the DKA of the storage apparatus identifies an HDD ofthe LU and stores the data.

In step 1500, the manager program determines whether the LU is in theready mode or not if the TOV indicator is not Online (1504). If so, theprocessing moves to the data storage processing (1502). If not on theother hand, the processing moves to HDD power supply control processing(1506). In the HDD power supply control processing, if the local memoryof the file server stores the first management table and the secondmanagement table, the power supply control processing in FIG. 10 isperformed. If the local memory of the file server stores the secondmanagement table, the power supply control processing in FIG. 13 isperformed. After that, the processing moves to the data storageprocessing (1502). In this way, by determining whether the TOV indicatorof the LU is online data or not, whether the LU is already in the readymode or not can be checked, and efficient data storage can be performed.

FIG. 16 shows another embodiment as a variation example in FIG. 9. Sincethe processing in the steps 900 to 908 is the same as that in FIG. 9,the same reference numerals are given. The subsequent processing will bedescribed in a case where the local memory of the file server stores thefirst management table and the second management table and in a casewhere the local memory of the file server stores the second managementtable below.

If the local memory of the file server stores the first management tableand the second management table, Request Manager in the file serverdetermines whether the disk drive unit to which the LU to store databelongs is in the ready mode or not (1600). If not, whether other diskdrive units have other LUs in the ready mode or not is determined(1606). If no LUs in the ready mode are available, the processing in andafter 1506 in FIG. 15 is performed, whereby the HDDs included in thedestination LU are shifted into the ready mode. If any other LU in theready mode is available, in order to store data to the other LU, thefile server identifies the destination HDD with reference to the firstmanagement table and instructs the data storage to the storage apparatus(1608). After that, in asynchronization with the data storage, the LUbeing the destination of the file is shifted into the ready mode, andthe file is moved from the other LU to the destination LU (1610).

If the disk drive unit to which the LU to store the data belongs is inthe ready mode (1600), Request Manger of the file server checks whetherthe HDDs included in the destination LU are in the ready mode or notbased on the first management table. If not, the processing moves to1606. If so, in order to store the data to the destination LU, the fileserver identifies the destination HDD based on the first managementtable and instructs the storage apparatus to store the data.

Next, the case will be described in which the local memory of the fileserver stores the second management table. The DKA of the storageapparatus determines whether the disk drive unit to which the LU tostore data belongs is in the ready mode or not (1600). If not, whetherany other LUs in the ready mode are available in other disk driveapparatus or not is determined (1606). If not LUs in the ready mode areavailable, the processing in and after 1506 in FIG. 15 is performed, andthe HDDs included in the destination LU are shifted to the ready mode.If any other LUs in the ready mode are available, in order to store datato the other LU, the storage apparatus identifies the destination HDDbased on the first management table and stores the data (1608). Afterthat, in asynchronization with the data storage, the LU being thedestination of the file is shifted into the ready mode, and the file ismoved from the other LU to the destination LU (1610).

If the disk drive unit to which the LU to store the data belongs is inthe ready mode (1600), the DKA of the storage apparatus checks whetherthe HDDs included in the destination LU are in the ready mode or notbased on the first management table. If not, the processing moves to1606. If so, in order to store the data to the destination LU, the DKAof the storage apparatus identifies the destination HDD based on thefirst management table and instructs the storage apparatus to store thedata.

The file movement processing in the 1610 applies a file management tablein FIG. 17. The file management table includes the name of a file,information on a near line or offline folder 1 to originally store nearline data or off line data (or the LU# corresponding to the folder andthe logical address) and information on a online folder 2 provisionallystoring the data (or the LU# corresponding to the folder and the logicaladdress).

The file management table is stored in the LM (22) of the file server.Storage Manager of the file server reviews the file management tableperiodically. If the number of file names is equal to or higher than apredetermined value, the data is moved from the online LU to the nearline or offline LU. Alternatively, the processing may be performed aftera lapse of a predetermined period of time.

1. A storage system comprising: a file server coupling with a computerthrough a network; and a storage apparatus coupling with the file serverthrough a network, wherein: the file server includes a first controller;the storage apparatus includes multiple storage devices having multiplestorage areas and a second controller that controls accesses to themultiple storage areas; each of the multiple storage areas has at leastone power saving mode among multiple power saving modes with differentshift times from the power saving modes to a ready mode; the firstcontroller: in response to the reception of data from the computer, setsan indicator to the data, the indicator relating to performance ofresponse to an access from the computer; and refers to the set indicatorof the data and selects a first storage area having the power savingmode satisfying the indicator; and the second controller: stores thedata to the first storage area.
 2. The storage system according to claim1, wherein the indicator is an indicator relating to a period of timefrom the transmission of an access request by the computer to thereception of a completion report.
 3. The storage system according toclaim 2, wherein the multiple power saving modes include a mode thatshuts down the power supply to the storage device.
 4. The storage systemaccording to claim 3, wherein: the file server further includes a memorythat stores metadata relating to the data transmitted from the computer;and the first controller sets the indicator to the metadata.
 5. Thestorage system according to claim 4, wherein: the file server furtherincludes a file system that defines a folder in which data is stored;the indicator is set to the folder; and after the data transmitted fromthe computer is stored in the folder, the indicator set to the folder isset to the metadata of the data.
 6. The storage system according toclaim 3, wherein the second controller shifts a ready mode of thestorage area to the power saving mode after a predetermined period oftime from the last access time is passed.
 7. The storage systemaccording to claim 1, wherein; if the first storage area is in the powersaving mode, the first controller selects a second storage area in theready mode; the second controller stores the data in the second storagearea; the second controller shifts the power saving mode of the firststorage area to the ready mode; and the second controller migrates thedata from the second storage area to the first storage area.
 8. Thestorage system according to claim 1, wherein: the file server furtherincludes a memory that stores a table showing the relationship between astorage area and a storage device; and the first controller specifies afirst storage device included in the first area and transmits to thestorage apparatus an instruction to store the data to the first storagedevice.
 9. The storage system according to claim 8, wherein: the tablemanages the current operation mode of a storage device; and if the firststorage device is in a power saving mode, the first controller transmitsto the storage apparatus an instruction to shift the power saving modeof the first storage device into a ready mode.
 10. A control method fora storage system, the storage system having: a file server coupling witha computer through a network; and a storage apparatus coupling the fileserver through a network, the storage apparatus including multiplestorage devices having multiple storage areas and controlling accessesto the multiple storage areas, the method comprising the steps of;setting each of the multiple storage areas in at least one power savingmode among multiple power saving modes with different shift times fromthe power saving modes to a ready mode by the storage apparatus; settingan indicator relating to the performance of response to an access fromthe computer to the data received from the computer by the file server;and referring to the set indicator of the data and selecting a firststorage area having the power saving mode satisfying the indicator bythe file server; and storing the data to the first storage area by thestorage apparatus.
 11. The control method for the storage systemaccording to claim 10, wherein the indicator is an indicator relating toa period of time from the transmission of an access request by thecomputer to the reception of a completion report.
 12. The control methodfor the storage system according to claim 11, wherein the storageapparatus sets at least one of the multiple storage areas in a mode thatshuts down the power supply to the storage device.
 13. The controlmethod for the storage system according to claim 12, wherein: the fileserver sets metadata relating to the data transmitted from the computerand sets the indicator to the metadata.
 14. The control method for thestorage system according to claim 13, wherein: the indicator is set to afolder in which data is stored in the file system of the file server;and after the data transmitted from the computer is stored in thefolder, the indicator set to the folder is set to the metadata of thedata.
 15. The control method for the storage system according to claim12, wherein the storage apparatus shifts a ready mode of the storagearea to the power saving mode after a predetermined period of time fromthe last access time is passed.
 16. The control method for the storagesystem according to claim 10, wherein: if the first storage area is inthe power saving mode, the file server selects a second storage area inthe ready mode; the storage apparatus stores the data in the secondstorage area, shifts the power saving mode of the first storage area tothe ready mode and then moves the data from the second storage area tothe first storage area.
 17. The control method for the storage systemaccording to claim 10, wherein: the file server identifies a firststorage device included in the first area based on a table showing therelationship between the multiple storage areas and the multiple storagedevices and transmits to the storage apparatus an instruction to storethe data to the first storage device.
 18. The control method for thestorage system according to claim 17, wherein: the file serverrecognizes the current operation mode of the first storage device basedon the table, and if the first storage device is in the power savingmode, the file server transmits to the storage apparatus an instructionto shift the first storage device into the ready mode.